Structure,Function and Properties of Immune cells.pdf

Structure,Function and properties of
T cell,B cell,Dendritic cell,stem cell,Macrophages,NK cell,Mast cell ,Basophil,Eosinophil & Neutrophil

1. STRUCTUREFUNCTIONANDPROPERTIESOFSTEMCELL
Stemcellsareunspecializedcellsthatcandevelopintodifferenttypesofcellsinthebody.Theyhavetwo
keyproperties:
Self-renewal:Stemcellscandivideandproducenewstemcells,whichallowsthemtomaintaina
populationofstemcellsinthebody.
Differentiation:Stemcellscandifferentiateintospecializedcells,suchasmusclecells,nervecells,or
bloodcells.
Stemcellsarefoundinallmulticellularorganisms,includinghumans.Theyplayanimportantrolein
development,growth,andrepair.
Structure
Stemcellshaveasimplestructure,similartootherundifferentiatedcells.Theyhavealargenucleuswith
prominentnucleoliandacytoplasmthatisrelativelysparseinorganelles.Stemcellsalsohaveahigh
nuclear-to-cytoplasmicratio.
Function
Stemcellshaveavarietyoffunctionsinthebody,including:
Development:Stemcellsareessentialforembryonicdevelopment.Theygiverisetoallofthedifferent
celltypesinthebody.
Growth:Stemcellsarealsoinvolvedinpostnatalgrowthanddevelopment.Theyhelptorepairdamaged
tissuesandreplacecellsthatarelostduetowearandtear.
Repair:Stemcellsarealsoinvolvedinrepairingdamagedtissues.Forexample,hematopoieticstemcells
inthebonemarrowproducenewbloodcellstoreplacethosethatarelostduetoinjuryordisease.
Properties
Stemcellshavethreekeyproperties:
Self-renewal:Stemcellscandivideandproducenewstemcells,whichallowsthemtomaintaina
populationofstemcellsinthebody.
Differentiation:Stemcellscandifferentiateintospecializedcells,suchasmusclecells,nervecells,or
bloodcells.
Potency:Stemcellsareclassifiedaccordingtotheirpotency,whichistheirabilitytodifferentiateinto
differentcelltypes.Pluripotentstemcellscandifferentiateintoanytypeofcellinthebody,while
multipotentstemcellscanonlydifferentiateintoalimitednumberofcelltypes.
Typesofstemcells
Therearetwomaintypesofstemcells:embryonicstemcellsandadultstemcells.
Embryonicstemcells:Embryonicstemcellsarederivedfromtheinnercellmassofablastocyst,whichis
anearlystageembryo.Embryonicstemcellsarepluripotent,meaningthattheycandifferentiateintoany
typeofcellinthebody.
Adultstemcells:Adultstemcellsarefoundinvarioustissuesthroughoutthebody.Theyaremultipotent,
meaningthattheycanonlydifferentiateintoalimitednumberofcelltypes.
Stemcellresearchisarapidlygrowingfieldwiththepotentialtorevolutionizemedicine.Stemcellsare
beingstudiedaspotentialtreatmentsforavarietyofdiseases,includingcancer,heartdisease,and
Alzheimer'sdisease.

2. STRUCTUREFUNCTIONANDPROPERTIESOFTCELL
Tcellsareatypeofwhitebloodcellthatplaysacentralroleintheadaptiveimmunesystem.Theyare
responsibleforrecognizinganddestroyinginfectedcellsandcancercells.Tcellsarealsoinvolvedin
regulatingtheimmunesystemandpreventingautoimmunediseases.
Structure
Tcellsaresmall,roundcellswithalargenucleusandabundantcytoplasm.Theyhaveavarietyofsurface
proteinsthatareinvolvedintheirfunction,including:
Tcellreceptor(TCR):TheTCRisresponsibleforrecognizingantigens,whichareforeignsubstancesthat
triggeranimmuneresponse.
CD3:CD3isaproteincomplexthatisessentialforTCRsignaling.
CD4andCD8:CD4andCD8areproteinsthathelpTcellstointeractwithotherimmunecells.
Function
Tcellshaveavarietyoffunctionsinthebody,including:
Recognizinganddestroyinginfectedcells:Tcellsrecognizeinfectedcellsbybindingtoantigensthatare
presentedonthesurfaceoftheinfectedcells.OnceaTcellbindstoanantigen,itisactivatedandbegins
toreleasecytotoxicgranules,whichkilltheinfectedcell.
Regulatingtheimmunesystem:Tcellshelptoregulatetheimmunesystembyproducingcytokines,
whicharesignalingmoleculesthatcommunicatewithotherimmunecells.Cytokinescanhelptoactivate
orsuppresstheimmuneresponse,dependingonthetypeofcytokine.
Preventingautoimmunediseases:Tcellsplayaroleinpreventingautoimmunediseases,whichare
diseasesinwhichtheimmunesystemattacksthebody'sowntissues.Tcellscanhelptosuppress
autoimmuneresponsesbykillingautoreactiveTcells,whichareTcellsthatrecognizethebody'sown
tissuesasantigens.
Properties
Tcellshaveanumberofuniqueproperties,including:
Antigenspecificity:Tcellsarespecificforasingleantigen.ThismeansthataparticularTcellcanonly
recognizeandbindtoonespecificantigen.
Clonalexpansion:WhenaTcellisactivated,itdividesandproducesacloneofTcellsthatareall
specificforthesameantigen.ThisprocessallowstheimmunesystemtorapidlyexpandthenumberofT
cellsthatarespecificforaparticularpathogen.
Memory:Tcellscandevelopmemory,whichmeansthattheycanremembertheantigensthattheyhave
encounteredinthepast.Thisallowstheimmunesystemtorespondmorequicklyandeffectivelyto
reinfectionwiththesamepathogen.
TypesofTcells
TherearethreemaintypesofTcells:
CytotoxicTcells(CD8+Tcells):CytotoxicTcellsareresponsibleforkillinginfectedcellsandcancer
cells.
HelperTcells(CD4+Tcells):HelperTcellshelptoactivateotherimmunecells,includingcytotoxicT
cellsandBcells.
RegulatoryTcells(Tregs):RegulatoryTcellshelptosuppresstheimmunesystemandprevent
autoimmunediseases.
Tcellsareessentialfortheadaptiveimmunesystemtofunctionproperly.Theyplayacriticalrolein
protectingthebodyfrominfectionandcancer
Structure

3. STRUCTUREFUNCTIONANDPROPERTIESOFBCELL
Bcellsaresmall,roundcellswithalargenucleusandabundantcytoplasm.Theyhaveavarietyofsurface
proteinsthatareinvolvedintheirfunction,including:
Bcellreceptor(BCR):TheBCRisresponsibleforrecognizingantigens,whichareforeignsubstances
thattriggeranimmuneresponse.
IgD:IgDisanimmunoglobulinthatisfoundonthesurfaceofBcells.ItisthoughttoplayaroleinBcell
activation.
CD19,CD20,andCD22:CD19,CD20,andCD22areproteinsthatareinvolvedinBcellsignalingand
activation.
Function
Bcellshaveavarietyoffunctionsinthebody,including:
Producingantibodies:Antibodiesareproteinsthatbindtoantigensandhelptoneutralizethemormark
themfordestructionbyotherimmunecells.Bcellsproduceantibodiesthatarespecificfortheantigens
thattheyrecognize.
Presentingantigens:BcellscanalsopresentantigenstoTcells.ThisprocessisessentialforTcell
activation.
Regulatingtheimmunesystem:Bcellsproducecytokines,whicharesignalingmoleculesthat
communicatewithotherimmunecells.Cytokinescanhelptoactivateorsuppresstheimmuneresponse,
dependingonthetypeofcytokine.
Properties
Bcellshaveanumberofuniqueproperties,including:
Antigenspecificity:Bcellsarespecificforasingleantigen.ThismeansthataparticularBcellcanonly
recognizeandbindtoonespecificantigen.
Clonalexpansion:WhenaBcellisactivated,itdividesandproducesacloneofBcellsthatareall
specificforthesameantigen.ThisprocessallowstheimmunesystemtorapidlyexpandthenumberofB
cellsthatarespecificforaparticularpathogen.
Memory:Bcellscandevelopmemory,whichmeansthattheycanremembertheantigensthattheyhave
encounteredinthepast.Thisallowstheimmunesystemtorespondmorequicklyandeffectivelyto
reinfectionwiththesamepathogen.
TypesofBcells
TherearetwomaintypesofBcells:
NaiveBcells:NaiveBcellsareimmatureBcellsthathavenotyetencounteredanantigen.
ActivatedBcells:ActivatedBcellsareBcellsthathaveencounteredanantigenandareproducing
antibodiesorpresentingtheantigentoTcells.
ActivatedBcellscanfurtherdifferentiateintodifferentsubtypesofBcells,including:
Plasmacells:PlasmacellsarespecializedBcellsthatproduceantibodies.
MemoryBcells:MemoryBcellsareBcellsthatremembertheantigensthattheyhaveencounteredinthe
past.Theycanquicklydifferentiateintoplasmacellsifthesamepathogenisencounteredagain.
Bcellsareessentialfortheadaptiveimmunesystemtofunctionproperly.Theyplayacriticalrolein
protectingthebodyfrominfection.

4. Inadditiontothepropertieslistedabove,Bcellsalsohaveanumberofotherimportantproperties,
including:
Bcellscanbeactivatedintwoways:Tcell-dependentactivationandTcell-independentactivation.
Bcellscanproduceavarietyofdifferenttypesofantibodies:IgG,IgA,IgM,IgD,andIgE.Eachtypeof
antibodyhasadifferentfunction.
Bcellscaninteractwithotherimmunecells,suchasTcells,dendriticcells,andmacrophages,to
coordinatetheimmuneresponse.
Bcellsarefascinatingandcomplexcellsthatplayavitalroleinprotectingthebodyfrominfection.
STRUCTUREFUNCTIONANDPROPERTIESOFNKCELL
Structure
Naturalkiller(NK)cellsarelargegranularlymphocytesthatareapartoftheinnateimmunesystem.They
havealargenucleuswithprominentnucleoliandacytoplasmthatisabundantinlyticgranules.NKcells
alsohaveavarietyofsurfaceproteinsthatareinvolvedintheirfunction,including:
Activatingreceptors:ActivatingreceptorsbindtoligandsontargetcellsandtriggerNKcellactivation.
Inhibitoryreceptors:InhibitoryreceptorsbindtoligandsonhealthycellsandpreventNKcellactivation.
Adhesionmolecules:AdhesionmoleculeshelpNKcellstobindtotargetcells.
Function
NKcellshaveavarietyoffunctionsinthebody,including:
Killinginfectedcellsandcancercells:NKcellscankillinfectedcellsandcancercellsbyreleasing
cytotoxicgranules,whichcontainproteinsthatcandamageorkillthetargetcell.
Regulatingtheimmunesystem:NKcellsproducecytokines,whicharesignalingmoleculesthat
communicatewithotherimmunecells.Cytokinescanhelptoactivateorsuppresstheimmuneresponse,
dependingonthetypeofcytokine.
Promotingwoundhealing:NKcellscanhelptopromotewoundhealingbyreleasinggrowthfactorsand
othersignalingmolecules.
Properties
NKcellshaveanumberofuniqueproperties,including:
Antigen-independentactivation:NKcellscanbeactivatedwithouttheneedforantigenrecognition.
Rapidresponse:NKcellscanrespondtoinfectionandcancerquickly,withouttheneedforpriorexposure
tothepathogenorcancercell.
Cytotoxicity:NKcellscankillinfectedcellsandcancercellsbyreleasingcytotoxicgranules.
TypesofNKcells
TherearetwomaintypesofNKcells:
MatureNKcells:MatureNKcellsarethemostcommontypeofNKcell.Theyarefoundinthe
peripheralbloodandspleen.
ImmatureNKcells:ImmatureNKcellsarefoundinthebonemarrow.TheydevelopintomatureNKcells
overtime.
NKcellsareessentialfortheinnateimmunesystemtofunctionproperly.Theyplayacriticalrolein
protectingthebodyfrominfectionandcancer.

5. AdditionalpropertiesofNKcells
Inadditiontothepropertieslistedabove,NKcellsalsohaveanumberofotherimportantproperties,
including:
NKcellscaninteractwithotherimmunecells,suchasTcells,dendriticcells,andmacrophages,to
coordinatetheimmuneresponse.
NKcellscanbeactivatedbyavarietyofdifferentstimuli,includingstress,inflammation,andcytokines.
NKcellscanbeeducatedbyotherimmunecellstobecomemorespecificintheirtargetingofinfected
cellsandcancercells.
NKcellsarefascinatingandcomplexcellsthatplayavitalroleinprotectingthebodyfrominfectionand
cancer.
STRUCTUREFUNCTIONANDPROPERTIESOFMACROPHAGES
Structure
Macrophagesarelarge,roundcellswithalargenucleusandabundantcytoplasm.Theyhaveavarietyof
surfaceproteinsthatareinvolvedintheirfunction,including:
Phagocyticreceptors:Phagocyticreceptorsbindtoparticlesontargetcellsandtriggermacrophage
engulfmentoftheparticle.
Tolling-likereceptors(TLRs):TLRsbindtomoleculesonpathogensandtriggermacrophageactivation.
Majorhistocompatibilitycomplex(MHC)molecules:MHCmoleculespresentantigenstoTcells,which
helpstoactivatetheadaptiveimmuneresponse.
Function
Macrophageshaveavarietyoffunctionsinthebody,including:
Phagocytosis:Macrophagescanengulfanddestroyforeignparticles,suchasbacteria,viruses,anddead
cells.
Antigenpresentation:MacrophagescanpresentantigenstoTcells,whichhelpstoactivatetheadaptive
immuneresponse.
Cytokineproduction:Macrophagesproducecytokines,whicharesignalingmoleculesthatcommunicate
withotherimmunecells.Cytokinescanhelptoactivateorsuppresstheimmuneresponse,dependingon
thetypeofcytokine.
Woundhealing:Macrophagesplayaroleinwoundhealingbypromotingtissuerepairandremodeling.
Properties
Macrophageshaveanumberofuniqueproperties,including:
Plasticity:Macrophagesareplasticcells,meaningthattheycanchangetheirfunctioninresponsetotheir
environment.Forexample,macrophagescandifferentiateintodifferentsubtypesofmacrophagesthatare
specializedfordifferenttasks,suchasphagocytosis,antigenpresentation,orcytokineproduction.
Heterogeneity:Thereisagreatdealofheterogeneityamongmacrophages,evenwithinthesametissue.
Thisheterogeneityisthoughttoreflectthedifferentrolesthatmacrophagesplayindifferenttissues.
Longevity:Macrophagesarerelativelylong-livedcells.Theycansurviveformonthsorevenyearsinthe
body.

6. Typesofmacrophages
Thereareavarietyofdifferenttypesofmacrophages,eachwithitsownspecializedfunction.Some
examplesofmacrophagesubtypesinclude:
Alveolarmacrophages:Alveolarmacrophagesarefoundinthelungs.Theyarespecializedfor
phagocytosisofinhaledparticles,suchasdustandpollen.
Kupffercells:Kupffercellsarefoundintheliver.Theyarespecializedforphagocytosisofdamagedliver
cellsandbacteria.
Microglia:Microgliaarefoundinthebrainandspinalcord.Theyarespecializedforphagocytosisof
damagedneuronsandothercellsinthecentralnervoussystem.
Macrophagesareessentialfortheinnateandadaptiveimmunesystemstofunctionproperly.Theyplaya
criticalroleinprotectingthebodyfrominfectionandinjury.
Additionalpropertiesofmacrophages
Inadditiontothepropertieslistedabove,macrophagesalsohaveanumberofotherimportantproperties,
including:
Macrophagescaninteractwithotherimmunecells,suchasTcells,dendriticcells,andneutrophils,to
coordinatetheimmuneresponse.
Macrophagescanbeactivatedbyavarietyofdifferentstimuli,includingpathogens,cytokines,andstress.
Macrophagescanproduceavarietyofdifferentmolecules,includingnitricoxide,reactiveoxygen
species,andproteases,tohelpthemcarryouttheirfunctions.
Macrophagesarefascinatingandcomplexcellsthatplayavitalroleinprotectingthebodyfrominfection
andinjury.
STRUCTUREFUNCTIONANDPROPERTIESOFMASTCELL
Structure
Mastcellsarelarge,roundcellswithalargenucleusandabundantcytoplasm.Theyarefoundin
connectivetissuesthroughoutthebody,especiallynearbloodvesselsandnerves.Mastcellsarepacked
withgranulesthatcontainhistamine,heparin,andotherinflammatorymediators.
Function
Mastcellsplayacentralroleinallergicreactionsandinflammation.Whenmastcellsareactivated,they
releasetheirgranules,whichtriggeravarietyofresponses,including:
Vasodilation(wideningofbloodvessels)
Increasedvascularpermeability(leakinessofbloodvessels)
Smoothmusclecontraction
Recruitmentofotherimmunecells
Mastcellscanbeactivatedbyavarietyofstimuli,including:
Allergens(suchaspollen,dustmites,andpetdander)
Infections
Physicaltrauma
Stress

7. Properties
Mastcellshaveanumberofuniqueproperties,including:
Tissueresidency:Mastcellsareresidentcells,meaningthattheyremaininthetissueswheretheyare
produced.
Rapidresponse:Mastcellscanrespondtostimuliveryquickly,withinsecondstominutes.
Pleiotropy:Mastcellscanreleaseavarietyofdifferentmediators,whichallowsthemtohaveawide
rangeofeffectsontheimmunesystemandothertissues.
Typesofmastcells
Therearetwomaintypesofmastcells:
Mucosalmastcells:Mucosalmastcellsarefoundintheliningoftherespiratoryanddigestivetracts.
Theyarethoughttoplayaroleindefendingthebodyagainstinfectionandparasites.
Connectivetissuemastcells:Connectivetissuemastcellsarefoundinconnectivetissuesthroughoutthe
body.Theyarethoughttoplayaroleinwoundhealingandallergicreactions.
Roleindisease
Mastcellsplayaroleinavarietyofdiseases,including:
Allergicdiseases(suchasasthma,hayfever,andeczema)
Autoimmunediseases(suchasrheumatoidarthritisandlupus)
Mastocytosis(ararecancerofthemastcells)
Mastcellsarefascinatingandcomplexcellsthatplayavitalroleintheimmunesystem.Theyarealso
involvedinavarietyofdiseases,makingthemanimportanttargetforresearchanddrugdevelopment.
STRUCTUREFUNCTIONANDPROPERTIESOFDENDRITICCELL
Structure
Dendriticcells(DCs)arelarge,irregularcellswithalargenucleusandabundantcytoplasm.Theyare
characterizedbytheirlong,branchingdendrites,whichgivethematree-likeappearance.DCsalsohavea
varietyofsurfaceproteinsthatareinvolvedintheirfunction,including:
Majorhistocompatibilitycomplex(MHC)molecules:MHCmoleculespresentantigenstoTcells,which
helpstoactivatetheadaptiveimmuneresponse.
C-typelectinreceptors:C-typelectinreceptorsbindtocarbohydratesonpathogensandtriggerDC
activation.
Toll-likereceptors(TLRs):TLRsbindtomoleculesonpathogensandtriggerDCactivation.
Function
DCsareprofessionalantigen-presentingcells(APCs).Theyareresponsibleforcapturing,processing,and
presentingantigenstoTcells.Thisprocessisessentialfortheactivationoftheadaptiveimmune
response.
DCsalsoproducecytokines,whicharesignalingmoleculesthatcommunicatewithotherimmunecells.
Cytokinescanhelptoactivateorsuppresstheimmuneresponse,dependingonthetypeofcytokine.

8. Properties
DCshaveanumberofuniqueproperties,including:
Immaturity:DCsareimmaturewhentheyleavethebonemarrow.Theymatureastheymigratetothe
tissues,wheretheyareexposedtoantigens.
Migratorycapacity:DCsarehighlymigratorycells.Theycanmigratefromthetissuestothelymphoid
organs,wheretheypresentantigenstoTcells.
Potency:DCsarethemostpotentAPCs.TheyareabletoactivatenaiveTcells,whichareTcellsthat
haveneverencounteredanantigenbefore.
TypesofDCs
TherearethreemaintypesofDCs:
ConventionalDCs(cDCs):cDCsarethemostcommontypeofDC.Theyarefoundinthetissuesand
lymphnodes.
PlasmacytoidDCs(pDCs):pDCsarefoundinthebloodandlymphnodes.Theyarespecializedforthe
productionoftypeIinterferons,whichareantiviralcytokines.
Monocyte-derivedDCs(moDCs):moDCsarederivedfrommonocytes,whichareatypeofwhiteblood
cell.Theyarefoundinthetissuesandblood.
DCsareessentialfortheadaptiveimmunesystemtofunctionproperly.Theyplayacriticalrolein
protectingthebodyfrominfectionandcancer.
AdditionalpropertiesofDCs
Inadditiontothepropertieslistedabove,DCsalsohaveanumberofotherimportantproperties,
including:
DCscaninteractwithotherimmunecells,suchasTcells,Bcells,andNKcells,tocoordinatethe
immuneresponse.
DCscanbeactivatedbyavarietyofdifferentstimuli,includingpathogens,cytokines,andstress.
DCscanbeeducatedbyotherimmunecellstobecomemorespecificintheirtargetingofantigens.
DCsarefascinatingandcomplexcellsthatplayavitalroleinprotectingthebodyfrominfectionand
cancer.Theyarealsobeinginvestigatedaspotentialtargetsforimmunotherapy,whichisatypeofcancer
treatmentthatusesthebody'sownimmunesystemtofightcancer

9. Allthreecelltypesaregranulocytes,meaningthattheyhavegranulesintheircytoplasm.Theyarealsoall
involvedintheinnateimmunesystem,whichisthebody'sfirstlineofdefenseagainstinfection.
Basophilsareinvolvedinallergicreactionsandinflammation.Whenbasophilsareactivated,theyrelease
theirgranules,whichtriggeravarietyofresponses,includingvasodilation,increasedvascular
permeability,andsmoothmusclecontraction.
Eosinophilsareinvolvedinparasiticinfectionsandallergicreactions.Theycankillparasitesbyreleasing
theirgranulesandbyphagocytosis.Eosinophilsalsoplayaroleinwoundhealing.
Neutrophilsarethemostabundanttypeofgranulocyte.Theyarethefirstresponderstoinfectionandplay
avitalroleinprotectingthebodyfrombacteriaandotherpathogens.Neutrophilscankillpathogensby
phagocytosisandbyreleasingtheirgranules.
STRUCTUREFUNCTIONANDPROPERTIESOFBASOPHIL
Structure
Basophilsaretheleastabundanttypeofgranulocyte,makinguplessthan1%ofallwhitebloodcells.
Theyarelarge,roundcellswithalargenucleusandabundantcytoplasm.Theirgranulescontain
histamine,heparin,andotherinflammatorymediators.
Function
Basophilsareinvolvedinallergicreactionsandinflammation.Whenbasophilsareactivated,theyrelease
theirgranules,whichtriggeravarietyofresponses,including:
Vasodilation(wideningofbloodvessels)
Increasedvascularpermeability(leakinessofbloodvessels)
Smoothmusclecontraction
Recruitmentofotherimmunecells
Basophilscanbeactivatedbyavarietyofstimuli,including:
Allergens(suchaspollen,dustmites,andpetdander)
Infections
Physicaltrauma
Stress
Properties
Basophilshaveanumberofuniqueproperties,including:
Tissueresidency:Basophilsareresidentcells,meaningthattheyremaininthetissueswheretheyare
produced.
Rapidresponse:Basophilscanrespondtostimuliveryquickly,withinsecondstominutes.
Pleiotropy:Basophilscanreleaseavarietyofdifferentmediators,whichallowsthemtohaveawiderange
ofeffectsontheimmunesystemandothertissues.
Additionalproperties
Basophilscaninteractwithotherimmunecells,suchasTcells,dendriticcells,andmastcells,to
coordinatetheimmuneresponse.
Basophilscanbeactivatedbyavarietyofdifferentstimuli,includingpathogens,cytokines,andstress.

10. Basophilscanproduceavarietyofdifferentmolecules,includingnitricoxide,reactiveoxygenspecies,
andproteases,tohelpthemcarryouttheirfunctions.
Roleindisease
Basophilsplayaroleinavarietyofdiseases,including:
Allergicdiseases(suchasasthma,hayfever,andeczema)
Autoimmunediseases(suchasrheumatoidarthritisandlupus)
Mastocytosis(ararecancerofthemastcells)
Basophilsarefascinatingandcomplexcellsthatplayavitalroleintheimmunesystem.Theyarealso
involvedinavarietyofdiseases,makingthemanimportanttargetforresearchanddrugdevelopment
STRUCTUREFUNCTIONANDPROPERTIESOFNEUTROPHIL
Structure
Neutrophilsarethemostabundanttypeofwhitebloodcell,makingupabout60%ofallwhitebloodcells.
Theyarelarge,multilobednucleusandabundantcytoplasm.Theirgranulescontainmyeloperoxidase,
lysozyme,andotherproteins.
Function
Neutrophilsarethefirstresponderstoinfection.Theyarephagocyticcells,meaningthattheycanengulf
anddestroybacteriaandotherpathogens.Neutrophilsalsoreleaseavarietyofantimicrobialsubstances,
suchasmyeloperoxidaseandreactiveoxygenspecies,tokillpathogens.
Properties
Neutrophilshaveanumberofuniqueproperties,including:
Rapidresponse:Neutrophilscanberecruitedtothesiteofinfectionwithinminutesofexposuretoa
pathogen.
Phagocytosis:Neutrophilscanengulfanddestroybacteriaandotherpathogens.
Killingofpathogens:Neutrophilsreleaseavarietyofantimicrobialsubstancestokillpathogens.
Additionalproperties
Neutrophilscaninteractwithotherimmunecells,suchasdendriticcellsandmacrophages,tocoordinate
theimmuneresponse.
Neutrophilscanbeactivatedbyavarietyofdifferentstimuli,includingpathogens,cytokines,andstress.
Neutrophilscanproduceavarietyofdifferentmolecules,includingnitricoxide,reactiveoxygenspecies,
andproteases,tohelpthemcarryouttheirfunctions.
Roleindisease
Neutrophilsplayaroleinavarietyofdiseases,including:
Infections:Neutrophilsareessentialforfightinginfections.However,excessiveneutrophilactivationcan
leadtotissuedamageandinflammation.
Autoimmunediseases:Neutrophilscanalsoplayaroleinautoimmunediseases,suchasrheumatoid
arthritisandlupus.
Cancer:Neutrophilscanalsobeinvolvedincancerdevelopmentandprogression.

11. Neutrophilsarefascinatingandcomplexcellsthatplayavitalroleintheimmunesystem.Theyhelpto
protectthebodyfromavarietyofinfectionsandotherdiseases.However,excessiveneutrophilactivation
canalsoleadtotissuedamageanddisease
STRUCTUREFUNCTIONANDPROPERTIESOFEOSINOPHIL
Structure
Eosinophilsarelarge,roundcellswithabilobednucleusandabundantcytoplasm.Theirgranulescontain
eosinophilperoxidase,majorbasicprotein,andotherproteins.
Function
Eosinophilsareinvolvedinparasiticinfectionsandallergicreactions.
Inparasiticinfections,eosinophilscankillparasitesbyreleasingtheirgranulesandbyphagocytosis.
Inallergicreactions,eosinophilsreleasehistamineandotherinflammatorymediators,whichcan
contributetothesymptomsofallergies.
Properties
Eosinophilshaveanumberofuniqueproperties,including:
Tissueresidency:Eosinophilsareresidentcells,meaningthattheyremaininthetissueswheretheyare
produced.Thisallowsthemtoquicklyrespondtoinfectionsandallergicreactionsinthetissues.
Rapidresponse:Eosinophilscanberecruitedtothesiteofinfectionorinflammationwithinminutesof
exposuretoastimulus.
Pleiotropy:Eosinophilscanreleaseavarietyofdifferentmediators,whichallowsthemtohaveawide
rangeofeffectsontheimmunesystemandothertissues.
Additionalproperties
Eosinophilscaninteractwithotherimmunecells,suchasTcells,dendriticcells,andmastcells,to
coordinatetheimmuneresponse.
Eosinophilscanbeactivatedbyavarietyofdifferentstimuli,includingparasites,allergens,andcytokines.
Eosinophilscanproduceavarietyofdifferentmolecules,includingnitricoxide,reactiveoxygenspecies,
andproteases,tohelpthemcarryouttheirfunctions.
Roleindisease
Eosinophilsplayaroleinavarietyofdiseases,including:
Parasiticinfections:Eosinophilsareessentialforfightingparasiticinfections.However,excessive
eosinophilactivationcanleadtotissuedamageandinflammation.
Allergicdiseases:Eosinophilsarealsoinvolvedinallergicdiseases,suchasasthma,hayfever,and
eczema.
Autoimmunediseases:Eosinophilscanalsoplayaroleinautoimmunediseases,suchasrheumatoid
arthritisandlupus.
Eosinophilicdisorders:Eosinophilicdisordersareagroupofrarediseasesthatarecharacterizedby
excessiveeosinophilactivationandinfiltrationoftissues.
Eosinophilsarefascinatingandcomplexcellsthatplayavitalroleintheimmunesystem.Theyhelpto
protectthebodyfromavarietyofinfectionsandallergicreactions.However,excessiveeosinophil
activationcanalsoleadtotissuedamageanddisease.